Motion picture projectorcontrol sysiem

ABSTRACT

A CONTROL SYSTEM FOR A MOTION PICTURE PROJECTION INSTALLATION HAVING A PAIR OF LENGTHS OF MOTION PICTURE FILM PASSED ALONG SEPARATE FILM PATHS THROUGH SEPARATE REVERSIBLE DRIVE MEANS BETWEEN A PAIR OF REELS UPON WHICH THE FILMS ARE COWOUND IN RECIPROCAL HEAD-TO-TAIL BIFLAR RELATION. THE CONTROL SYSTEM INCLUDES MEANS FOR SENSING THE QUANTITY OF FILM PRESENT IN ONE OF THE FILM PATHS BETWEEN ONE REEL AND FILM DISPLAY MEANS LOCATED INTERMEDIATE THE REELS. THE CONTROL SYSTEM ALSO INCLUDES MEANS FOR CONTROLLING THE DRIVE MEANS TO MAINTAIN SAID FILM QUANTITY BETWEEN PREDETERMINED LIMITS.

Jan. 5, 1971 J. K. TAILLON MOTION PICTURE PROJECTOR CONTROL SYSTEM Filed Feb. 5, 1969 Jan. 5, 1971 J. K. TAILLON MOTION PICTURE PROJECTOR CONTROL SYSTEM 15 Shee [JD-Sheet 2 Filed Feb. 5, 1969 J. K. TAILLON MOTION PICTURE PROJECTOR CONTROL SYSTEM Jan. 5, 1971 Filed Feb. 3, 1969 15 Shee L$Sheut TNT MAT

TNT

m MT m mu Jan. 5, 1971 J. K. TAILLON 3,552,342

MOTION PICTURE PROJECTOR CONTROL SYSTEM Filed Feb. 5, 1969 15 Sheena-Sheet 4 m; m m! 9/ Jan. 5, 1971 J. K. TAILLON 3,552,842

MOTION PICTURE PROJECTOR CONTROL SYSTEM Filed Feb. 3, 1969 15 Sheens-Sheet 6 Jan. 5, 1971 J. K. TAILLON 3,552,842

MOTION PICTURE PROJECTOR CONTROL SYSTEM Filed Feb. 5, 1969 l5 ShBGLS-3l19et '7 Jan. 5, 1971 Filed Feb. 5, 1969 J. K. TAILLON MOTION PICTURE PROJECTOR CONTROL SYSTEM 15 Shee LsSheet f) 1971 J. K. TAILLON MOTION PICTURE PROJECTOR CONTROL SYSTEM 15 Shae LS-Shect 12 Filed Feb. 5, 1969 W1 J. K. TAILLON MOTION PICTURE PROJECTOR CONTROL SYSTEM 15 Sheeas-Sheat 13 Filed Feb. 5, 1969 .L jwmh J. K. TAILLON MOTION PICTURE PROJECTOR CONTROL SYSTEM l5 Sheew-Sheet 14.

Filed Feb. 5, 1969 NMN Ni A W IL Jam 5 1711 J. K. TAELLON MOTION PICTURE PROJECTOR CONTROL SYSTEM 15 Shee ns-Sheet 15 Filed. Feb. 5, 1969 United States Patent 3,552,842 MOTION PICTURE PROJECTOR CONTROL SYSTEM John Kellner Taillon, Sierra Madre, Califi, assignor to Bell & Howell Company, Pasadena, Calif., a corporation of Illinois Filed Feb. 3, 1969, Ser. No. 795,992 Int. Cl. G03b 21/02, 21/43 US. Cl. 352-125 28 Claims ABSTRACT OF THE DISCLOSURE FIELD OF THE INVENTION This invention pertains to electromechanical control systems for regulating the operation of a motion picture projection installation which incorporates a pair of lengths of motion picture film cowound in reciprocal head-to-tail bifilar relation on a pair of reels defining the ends of two separate film paths.

BACKGROUND OF THE INVENTION US. Pat 3,379,488 describes a motion picture display system which has utility in the passenger compartment of commercial aircraft, as well as in classrooms and the like.

So that a motion picture projection system may have enhanced utility in such areas, it is desirable that the projection system be arranged for operation by relatively unskilled personnel such as airline stewardesses or teachers, rather than trained projectionists. Ideally, especially where the projection system is to be used to display a motion picture program of specified content a number of times, it is desirable that the need for rewinding film be minimized, if not altogether eliminated. The elimination of film rewinding is of particular economic significance where a projection system is used in the passenger aircraft of international air carriers; the servicing of such systems for the purposes of film rereeling involves the use of trained personnel which are not normally maintained on the staff of the carrier and which are obtainable in many countries only at premium wages, if at all.

To overcome the problems which, to date, have worked to the economic disadvantage of motion picture projection systems aboard the aircraft of international airlines, an improved motion picture projection system has been proposed. The improved projection system includes a pair of film storage reels and a pair of lengths of motion picture film cowound in reciprocal head-to-tail bifilar relation upon the reels. The films are passed along separate paths between the reels through projection means located intermediate the reels. Separate film advance mechanisms, each having a reversible drive motor, are associated with the films between the reels for driving the film lengths between the reels. The film lengths define respective halves of a motion picture program of specified content; that is, each film may define a separate ice feature-length motion picture, or the two film lengths may define respective halves of a single feature-length motion picture. During operation of the system, the information carried by that film which moves in a forward mode between the reels is displayed, the information carried by the other film length being displayed when the films move in the opposite direction between the reels.

It is inherent in this projection system that the films are in the same state upon completion of display of the entire program as they were at the time display of the program was commenced. This feature is significant because the system may be operated repeatedly to display the same program without rereeling the film between program presentations; of course, it is necessary to remove the film from the system if the content of the program is to be changed. Such a motion picture projection system is readily usable in the passenger compartments of aircraft operated by international air carriers, as well as in classrooms, small theatres, and in myriad other situations. In any of these usages, however, it is desirable that the projection system be essentially self-regulating so that the person responsible for operation of the system need not do much more than merely turn the system ON to commence program display and turn the system OFF when the program display is completed.

The presently preferred use of this projection system is in the passenger compartments of commercial passenger aircraft.

SUMMARY OF THE INVENTION This invention provides a control system for the improved motion picture projection system described above. The control system provides automatic control over the rate at which film is taken from and supplied to the reels, and also automatically regulates the amount of film which is present in the respective film paths. The control system is arranged to minimize the attention which an operator must give to the projection system during its operation. The control system is arranged so that the equipment required to achieve the desired control functions is minimized, and so that the nature of the film paths between the two reels may be as simple as possible. The simplification of the film paths extends the useful life of the film itself, and increases the number of times the system may be operated to display the same program before the film must be removed from the projection system for cleaning and conditioning. These desirable features of the control system flow from the fact that, due to the cowound bifilar relation of the films on the reels, the basic behavior of one film is reflected in the basic behavior of the other film. That is, in general terms, each film is slaved to the other during movement of the films between the reels, and the necessary control functions provided by the control system are divided between the films so that film tension sensing operations required to generate the desired control signals are distributed substantially equally between the films. The system also has the feature that, upon completion of one mode of operation thereof, the system resets itself to provide appropriate control during subsequent operation of the system in the other mode; that is, the control system has a memory and remembers how it operated during the prior operation of the associated projection system.

Generally speaking, this invention provides a control apparatus for a motion picture projection system which includes a pair of film storage reels. A pair of film lengths are cowound on the reels in reciprocal head-totail bifilar relation, and are passed between the reels along separate film paths. Display means are located along the film paths between the reels. The projection system also includes reversible drive means associated with each film length along its path for driving the film between the reels. The control apparatus includes means for sensing a change in the quantity of film present in one of the film paths between one of the reels and the display means. The control apparatus also includes means responsive to the sensing means for controlling operation of the drive means when the sensing means discerns a change in film quantity in excess of a predetermined amount.

Preferably, the rate at which film is unreeled from and reeled upon the respective reels is controlled by information derived from one of the film lengths, and the rate at which the drive means are operated to move film between the reels is controlled from information derived from the other film path.

DESCRIPTION OF THE DRAWINGS The above-mentioned and other features of this invention are more fully set forth in the following detailed description of a presently preferred embodiment of the control system, which description is presented with reference to the accompanying drawings, where- FIG. 1 is a simplified schematic representation of the control system and its relation to a motion picture projection system of the type described above;

FIG. 2 is an elevation view of an operators central control panel;

FIG. 3 illustrates the relationship of the schematic diagrams of FIGS. 3A through 3K;

FIGS. 3A through 3K are schematic diagrams of separate portions of the control system, such diagrams being related to each other in the manner illustrated in FIG. 3;

FIG. 4 is a fragmentary elevation view of a portion of the mechanism provided adjacent each film storage reel for regulating the rotational rate of the reel; and

FIG. 5 is a cross-sectional elevation view of a portion of the structure shown in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT .Referring to FIG. 1, the presently preferred use of a control system according to this invention is in combination with a motion picture projection system 12 which includes a pair of projection stations 13 and 14 and a pair of reel stations 15 and v16. In the following description, projection station 13 is sometimes referred to as the No. 1 projection station, projection station 14 is sometimes referred to as the No. 2 projection station, reel station 15 is sometimes referred to as the No. 1 reel station, and reel station 16 is sometimes referred to as the No. 2 reel station.

Reel stations 15 and 16 include, respectively, reels 17 and 18 upon which are cowound, in reciprocal head-totail bifilar relation, a pair of film lengths 19 and 20; film length 19 is sometimes referred to hereinafter as the No. l film and film length 20 is sometimes referred to as the No. 2 film. Film lengths 19 and 20 define the first and second halves, respectively, of a motion picture program of specified content. A program of specified content may include two feature-length motion pictures, in which case reels 17 and 18 are of sufficient capacity to store both films essentially fully thereon. The term program of specified content also encompasses a single feature-length motion picture, in which case film length 19 defines the first half of the picture and film length 20 defines the second half of the picture. Film lengths 19 and 20 are of essentially equal length and are actually two separate lengths of film.

The reciprocal head-to-tail bifilar relation of film lengths 19 and 20 on reels 17 and 18 may be understood best by assuming that the motion picture program is constituted of a single feature-length motion picture. Assume further that the single film length is folded upon itself at its midlength so that the head end of the portion of the film defining the first half of the program is placed in overlying relation to the tail end of the portion of the film defining the second half of the program, and so that the tail end of the portion of the film defining the first half of the program is placed in overlying relation to the head end of the second half of the program. In this head-to-tail relationship, the film is wound upon reel 17 so that the tail end of the first half of the program and the head end of the second half of the program (i.e., the location where the film is folded on itself) are connected to the core of reel 17, and the head end of the first half of the program and the tail end of the second half of the program is connected to the core of reel 18. Between the reels, the separate halves of the film are threaded along separate film paths through projection stations 13 and 14, respectively. Because the halves of the folded film are wound in overlying relationship on reels 17 and 18, the film is properly said to be cowound in reciprocal head-to-tail bifilar relation upon the reels.

Projection system 12 has two modes in operation. In its A mode, the projection system is operated to move fil-m from reel 17 to reel 18. In its B mode, the projection system is operated to transfer film from reel 18 to reel 17. When the projection system is threaded with film according to the procedure described above and is operated in its A mode, the frames of film length 19 move in a forward sequence or mode through projection station 13, and the frames of film length 20 move in a reverse sequence or mode through projection station 14. Conversely, when the system is operated in its B mode, film length 19 moves in a reverse mode past optical axis 21 of projection station 13, and film length 20 moves in a forward mode past optical axis 22 of projection station 14.

Each of projection stations 13 and 14 defines what is substantially a conventional motion picture projector. Thus, projection station 13 includes a lens assembly 25 aligned along optical axis 21 between a pair of film drive sprocket 26; the sprockets constitute a part of an essentially conventional film advance mechanism driven by a reversible motor 27. Located in-line with optical axis 21, and on the opposite side of film length 19 from the projection lens assembly, is a projection lamp 28 which is located next to a spare projection lamp 29; the counterparts in projection station 14 of the components of station .13 are identified by corresponding primed numbers, this expedient being utilized for simplification of the illustration of FIG. 1. A fire shutter 30 is dispoced in projection station 13 between lamp '28 and the path of film 19, and is operated by a solenoid 31. Projection station 13 also includes a forward-mode shuttle-loop restoring mechanism 32; mechanism 32 is of conventional design and preferably is of the type encountered in commercially available motion picture projectors manufactured by Bell & Howell Company. Projection station 13 also includes a reverse-mode shuttle-loop restoring mechanism 33 which is of different design from mechanism 32 and constitutes a novel feature of the present invention.

Projection station 13 further includes an audio pickup device 34 which cooperates with film length 19 downstream of optical axis 20 during A mode operation of projection system 12. That is, audio pickup device 34 is located between optical axis 21 and reel 18 along the path of film length 19. Projection station 14 includes an audio pickup device 34 which is disposed between optical axis 22 and reel 17 along the path of film length 20. Audio pickup devices 34 and 34 may be of the optical type or of the magnetic type, as desired. In a presently preferred form of projection system 12, projection stations 13 and 14 are identical, and are arranged in erect side-by-side relation with optical axes 21 and 22 thereof directed to a common display screen. The positional reversal of audio pickup devices 34 and 34 relative to their repective film 1 length is obtained by the manner in which the film lengths are threaded through the projection system. This threading arrangement is not a part of the present invention and, therefore, is not described herein.

It will be observed from an examination of FIG. 1 that the locations of the forward-mode and the reversemode shuttle-loop restoring mechanisms of projector 13 are reversed relative to the corresponding components of projector 14, but occupy the same relative positions along the adjacent film paths when the respective films are moved in a forward mode through the projectors.

Projection lamps 28 and 29 of projection station 13 are mounted in side-by-side relation upon a spring loaded, slidable shuttle plate (not shown) which normally is positioned so that lamp 28 is aligned with optical axis 21, and similarly with projection lamps 28 and 29 of projection station 14. The shuttle plates are moved by the spring bias applied thereto upon operation of a corresponding spare lamp solenoid K12 and K16 (not shown in FIG. 1, but see FIG. 3) to move to their other limit of travel in which spare lamps 29 and 29', respectively, are aligned with the respective optical axes. Upon arrival of the appropriate shuttle plate at the limit which places the spare lamp in alignment with the respective optical axis, a limit switch S24 or S25 (not shown in FIG. 1, but see FIG. 3) is operated. The details of the spare lamp arrangement, the shuttle plates, and drive mechanisms therefor, are shown in commonly-owned copending application Ser. No. 639,462, filed May 18, 1967.

Fire shutters 30 and 30 are provided to protect film lengths 19 and 20, respectively, from exposure to heat from the projection lamps when the film lengths are stationary relative to the corresponding optical axes, thereby to prevent burning of the film. The fire shutters are also interposed between the projection lamps and the films during the interval following start-up of the projection system in either of its operational modes, within which interval the projection lamps heat up and assume their full operational brightness.

Each of film storage reels 17 and 18 is coupled to a reel drive motor 35 or 36, respectively, via a variably elfective coupling mechanism 37, 38, respectively. With reference to reel station 15, coupling mechanism 37 is controlled by the tension in film length 20 adjacent reel 17. Closely adjacent the periphery of reel 17, film length 20 passes around rollers 39, 40 and 41, each of which has a prime numbered counterpart in reel station 16. Rollers 39 and 41 are mounted for rotation about fixed axes, but roller 40 is mounted to a sensing lever 42 having a fulcrum 43. Lever 42 is connected to a biasing spring 44, and is connected by a pivoting linkage assembly 45 to a structure 46 of mechanism 37 which is engaged more directly between reel drive motor 35 and reel 17. Elements 39 through 46 are all components of coupling mechanism 37 and, similarly, at reel station 16, elements 39' and 46' are components of coupling mechanism 38. The coupling mechanisms are essentially identical and are effective to increase or decrease the driving connection of the reel drive motors with the respective reels depending upon (1) the tension of the film engaged with the sensing rollers thereof, and (2) whether the appropriate reel station is functioning to pay out or to reel in film within projection system 12. The connection of the reel drive motors with the corresponding film storage reels preferably is via a belt, and in this regard, mechanisms 37 and 38 are substantially in accord with the disclosures of US. Pat. 3,398,9l4 except to the extent illustrated in FIGS. 4 and 5 and described in greater detail hereinafter. Reel drive motors 35 and 36 preferably are reversible synchronous motors which are operated at constant speed. It should be observed at this point that the angular velocity of reels 17 and 18 is controlled by information derived from the state of the No. 2 film, i.e., film length 20.

Reel station 15 includes a normally closed end-of-film switch 48 which is operated by a sensing roller 49 which, during operation of projection system 12, rides against film length 19 to maintain the switch contacts in an open state. Reel station 16 includes a corresponding end-offilm switch 48'. Sensing rollers 49 and 49' are disposed in-line with the position occupied in film length 19 by control apertures 50 (see reel station 16) which are disposed at selected locations along film length 19. Preferably, apertures 50 are disposed adjacent the opposite ends of the film. As will be described below, the sensing of apertures 50 by either of switches 48 or 48' causes the projection system to be shut down, and also produces an adjustment in the state of the logical control mechanisms within control system 10; in this regard, it should be noted that the presently preferred use of projection system 12 is in the passenger compartment of a commercial aircraft in conjunction with a film program constituted of two full length motion pictures.

Projection station 15 includes a looper assembly 52 which is comprised of a plurality of rollers 53 mounted for rotation about stationary axes and a plurality of rollers 54 which are mounted to a common movable carriage 55 biased relative to rollers 53 by a constant force spring mechanism 56 to maintain essentially constant tension in film threaded through the looper in the manner illustrated schematically in FIG. 1. Roller carriage 55 cooperates with a slack sensing switch 57 and a tension sensing switch 58 which are located in spaced relation to each other along the path of movement of the carriage 55. Reel station 16 has associated with it a second looper assembly 60 which includes components 61 through 66 which correspond in structure and function to components 53 through 58, respectively, of looper assembly 52. Looper assembly 52 functions to sense a change in the quantity of film present in the path of film length -19 between reel 17 and projection station 13. Similarly, looper assembly 60 functions to sense a change in the quantity of film present in the path of film 19 between reel 18 and projection station 13. As will be described below, control system 10, to which switches 57, 58, 65 and 66 are connected, operates to provide corrective action within projection system 12 when the extent of change sensed by the looper assemblies exceeds a predetermined amount.

The operational mode (forward or reverse) of motors 27, 27, 35 and 36 of projection system 12 is determined by control system 10. Similarly, the operation of the forward-mode and reverse-mode shuttle-loop restoring mechanisms and of the fire shutter solenoids is regulated by the control system in response to information supplied to the control system by the end-of-film sensing switches and by the film slack and film tension sensing switches of the looper assemblies. The selection of which of the projection lamps and the audio pickup devices is operative at any given time is also determined by the operation of control system 10.

It will be observed from an examination of FIG. 1 that the signals which control the logical operation of the control system are all derived from the state of the No. 1 film, i.e., film length 19. As noted above, the signals which determine the rate at which reels 17 and 18 are driven by their respective drive motors is derived entirely from the No. 2 film. This association of distinct control functions within system 12 with respective ones of the two films present in the projection system is made possible because the films are reciprocally slaved to each other by reason of their cowound bifilar relation upon reels 17 and 18. That is, film length 19 is payed out from reel 17, or reeled onto reel 17, at the same rate as film length 20. Similarly, the presence of an excess quantity of film in the path of film length 19 between reel 17 and projection station 13 will, except in exceptional circumstances, be associated with a corresponding deficiency in the amount of film present in the same film path between projection station 13 and reel 18; similar excesses and deficiencies of film normally will occur in the corresponding portions of the path of film length 20..That is, because the bifilar relation of film lengths 19 and 20 upon reels 17 and 18 necessarily results in the film lengths being payed out from or taken onto the reels at equal rates at either reel station, but not necessarily at both reel stations, the operation of variably effective coupling mechanisms 37 and 38 may be controlled from only one of the film lengths. Similarly, as will be made clear from the following detailed description of the operation of control system 10, information derived from the looper assemblies may be used to advantage to control the movement of film length 20 through projection station 14. A change in the rate at which either film is moved through its projection station will have a corresponding effect in the state of looper mechanisms 52 and 60.

FIG. 1 should not be interpreted to suggest that all information gathering switches which have an effect upon control system 10 are associated with the reel stations or with the projection stations. As noted above, the presently preferred use of projection system 12 is in the passenger compartment of a commercial aircraft; actually, the aircraft includes three projection systems, each of which is in accord with the illustrations of FIG. 1 and the foregoing description. These three projection systems normally are controlled, at least as to film selection, START and STOP commands, and spare lamp injection, from a central control station defined by a stewardess control panel 69, an elevation view of which is provided in FIG. 2.

The face of the stewardess remote control panel is divided into three basic areas 70, 71 and 72, corresponding to the forward, center and aft projection systems installed within the aircraft. Each of panel areas 70, 71 and 72 includes a plurality of illuminated push button switches as follows: SHOW switch 73, CYCLE switch 74, START switch 75, MOVIE No. 1 switch 76, MOVIE No. 2 switch 77, OFF switch 78, and SPARE LAMP switch 79. The control panel 69 also includes an illuminated SEAT MUSIC push button switch 80 which is operable to supply stereophonic music to the headphone connections associated with the various seats in the aircraft, via the motion picture projection systems, in a manner which is conventional and does not form a part of this invention. Panel 69 also includes a key-operated POWER ON/ OFF switch 81 which is operable by the stewardess to connect the aircraft 400 cycle three-phase power system to the several control systems 10. A pair of holders 82 are mounted to the face of the control panel to receive legend cards bearing the names of the motion pictures defined by film lengths 19 and 20, respectively. Each of switches 73-78 is connected in parallel with a corresponding switch or relay located within a control box 84 located within the housing of the projection system to which the several switches are pertinent. Switch 81 is connected in series with a corresponding power switch S8 in each control system 10 within the aircraft.

Referring now to FIG. 3, and the several portions 3A-3K thereof which collectively set forth a schematic wiring diagram of control system 10, a plurality of leads 85-105 connect remote control panel 69 with the several identical control boxes 84 within the aircraft. These leads are designated as follows:

Lead

Designation 8 anism associated with that projection station operating in a forward mode in the projection system; lead 88 is energized by operation of switch 79 at remote control panel 69;

89 Spare lamp indicator which is energized by operation of the limit switch associated with the projection lamp shuttle plate associated with lead 88;

90 AC ground;

91 Cycle indicator which, when energized, produces illumination of push button 74 at the remote control panel;

92 Show indicator which, when energized, produces illumination of push button 73 at the remote control panel;

93 Show switch which is energized by operation of switch 73;

94 Off switch which is energized by switch 78 at the remote control panel;

95 Cycle switch which is energized by operation of switch 74;

96 115 v. AC in from control box 84 to remote control panel 69;

97 Off indicator which, when energized, produces illumination of push button 78 at the central remote control panel;

98 Start indicator which, when energized, produces illumination of push button 75;

99 115 v. AC return from central control panel 69 to control box 84;

100 Start switch which normally is energized by switch 75; 101 C-phase 400 Hz. power; 102 B-phase 400 Hz. power; 103 A-phase 400 Hz. power; 104 Minus DC 'bus; 105 Plus DC bus.

Each of leads 86-89, 91-95, and 97-100 is connected to minus DC bus 104 via the corresponding indicator lamp or push button switch located in remote control panel 69.

Control box 84 includes a plurality of relays which are designated K1, K2 Where these relays have multiple contacts, the contacts are designated 1, 2, 3, etc., proceeding downwardly through the vertically aligned contacts. That is, with reference to mode selector relay K8, the contacts thereof are designated K8-1, K8-2 K8-11. This convention is adhered to for simplicity of description in the following text.

Similarly, control system 10 includes several switches which are designated S1, S2 Where these switches have multiple contacts of significance, the contacts are designated 1, 2, 3, etc., proceeding vertically downwardly through the contact array in the accompanying drawings. Thus, with reference to phase selector switch S1, the contacts thereof are designated S1-1, SI-2, S1-3. This convention also is adhered to for the purposes of simplicity of description in the following text.

Three phase 400 Hz. power from the aircraft is supplied to the control system from central remote control panel 16 via leads 101, 102 and 103 to the contacts of main contactor relay K1. Three-phase power ON/OFF switch S8 is connected in series with contactor K1 from control panel 69 and is provided so that a technician, following operation of switch 81 at panel 69, may energize or deenergize the control system without having to walk back and forth between control box 84 and panel 69. During normal operation of the control system, switch S8 is closed so that energization of the control system is regulated by operation of switch 81 at control panel 69. Preferably, switch S8 is key operated like switch 81. The other switches of control panel 69 are all duplicated in control box 84, except for spare lamp switch 79, so that a servicing technician may service or test the control systern at the location of the system itself without repeatedly moving back and forth to remote control panel 69.

Lead 117 is connected in parallel with contacts K1-3 to 115 volt AC in lead 96 so that, upon closure of both of switches 81 and S8, C-phase main power is supplied to the energization terminals of a 28 volt DC power supply 119. The DC power supply has its minus output terminal connected to minus DC bus 104 and to the ground energization terminal of the power supply. The positive output terminal of the power supply is connected to plus DC bus 105.

' Energization of contactor K1 is controlled by operation of START switch S (connected in parallel with remote START switch 75) intimately associated with the down winding of START/STOP latching relay K4. Operation of relay K4 into its START mode completes a circuit via contact K4-1 and lead 120 from the minus DC bus to series-connected reel station lockout switches 89 and S (located in reel stations and 16, respectively, and interconnected by lead 121), switch S10 being connected to the coil of main contactor K1 via lead 122. Lockout switches 59 and S10 are associated with the DC gear motors provided in the reel stations for shifting a pivot point in each of linkages 45 and 45, thereby to reverse the control functions provided by mechanisms 37, 38 relative to reels 17 and 18, respectively.

FIG. 4 is an elevation view of the mechanism which is variably effective to couple reel drive motor 35 to reel 17 in reel station 15. The output shaft of reel drive motor 35 is connected to a belt drive pulley 122 which drives a belt 123 engaged with the periphery of a reel drive pulley 124 to which film storage reel 17 is coaxially mounted. Between pulleys 122 and 124, the belt is engaged with a tensioning pulley 125 mounted to a support arm 126 having a fixed pivot 127 at one end thereof. The other end of arm 126 is connected by pivot 128 to one end of a connecting link 129. The opposite end of link 129 is pivoted at 130 to a shift link 131 which is keyed to the output shaft 43 of a gear box 132 (see FIG. 5). As shown in FIG. 5, the input to the gear box is provided by a reversible DC motor 133. The gear box is disposed on the opposite side of a reel station chassis plate 134 from the structure shown in FIG. 4. Shaft 43 serves as the pivot point or fulcrum of sensing lever 42 (in this regard, see FIG. 1 and the description presented relative thereto).

A second connecting link 136 has one end thereof pivoted at 137 to the sensing lever adjacent fulcrum shaft 43. The other end of link 136 is pivoted at 138 to a brake shoe 139 which in turn is pivoted at 140 to chassis plate 134 for movement into frictional engagement with the periphery of reel drive pulley 124 in response to the bias of a spring 141.

When the elements illustrated in FIG. 4 are arranged in the position shown in solid lines, reel station 15 functions as a take-up device for film lengths 19 and 20. In such a situation, gear box output shaft 43 is so disposed angularly relative to sensing lever 42 that the pivotal connection at 130 between shift link 131 and connecting link 129 lies away from reel drive pulley 124 relative to a line through shaft 43 and tension sensing roller 40. As tension in film increases to move sensing lever 42 clockwise about shaft 43, support arm 126 is moved in such manner that the tension in belt 123 is decreased, thereby to decrease the effectiveness of the coupling between belt drive pulley 122 and reel drive pulley 124 via belt 123 and reduce the rate at which film is taken onto the reel. Conversely, when film length 20 becomes slack at sensing roller 40, spring 44 induces the sensing lever to move counterclockwise about shaft 43, thereby to increase the tension with which belt 123 is engaged between pulleys 122 and 124 and increase the rate at which the reel is driven by motor 35. During such operation of the structure shown in FIG. 4, brake shoe 139 idles relative to belt drive pulley 124. Clockwise rotation of the sensing lever about its fulcrum shaft 10 causes the brake shoe to be moved into more intimate engagement with the periphery of the reel drive pulley, but the direction of rotation of this pulley is such as to tend to move the brake shoe out of engagement with the pulley.

When projection system 12 is operated in its A mode, such that it is necessary for film storage reel 17 to function as a film supply reel, mechanism 46 is adjusted so that the manner in which movement of sensing lever 42 is effective upon drive belt 123 is reversed from that relationship described above. To accomplish this adjustment, motor- 133 is operated to rotate shaft 43 clockwise relative to sensing lever 42 to such extent that shift lever 131 assumes the position shown in dotted lines in FIG. 4. In this alternate position, the pivot of connecting link 129 to shift link 131 lies toward reel drive pulley 124 from a line through fulcrum shaft 43 and sensing roller 40. When reel station 15 functions to supply film to projection system 12, reel drive motor 35 is reversed to reverse the direction of rotation of belt drive pulley 122, as shown by the dashed arrows in FIG. 4. During operation of reel station 15 in a supply mode, clockwise movement of the sensing lever about fulcrum shaft 43, in response to an increase in tension in film 20, is effective to produce an increase in the tension of belt 123 on reel drive pulley 124, thereby to cause reel 17 to rotate faster and supply more film to projection station 14. Conversely, the presence of slack in film 20 at sensing roller 40 results in counterclockwise movement of the sensing lever about its fulcrum axis, thereby producing a reduction in drive belt tension and inducing the brake shoe to engage the periphery of the reel drive pulley more intimately. In this case, however, the direction of rotation of reel drive pulley 124 is such that increased engagement of the brake shoe with the pulley is effective to retard rotation of the supply reel 17, thereby reducing the rate at which film is payed out from the reel and increasing the tension in film 20. This is true because motor 27 associated with projection station 14 continues to operate at a constant rate, the rate of operation of motor 27 being altered only in response to control signals derived from the state of film 19 at loopers 52 and 60.

As shown in FIG. 5, sensing lever 42 is secured to a bearing ring 143 by screws 144. Bearing ring 143 rotatably journals shaft 43 and is itself rotatably mounted in a bushing 145 which is immovably mounted to chassis plate 134. Screws 144 pass through a standoff ring 146 and into gear box 132 which contains a motion reducing gear train 147 connected between shaft 43 and the shaft of DC motor 133. It is apparent, therefore, that gear box 132 and sensing lever 42 are fixed relative to each other angularly of the axis of shaft 43, and that the gear box moves relative to chassis plate 134 with and during movement of the sensing lever. It follows, therefore, that operation of motor 133 produces rotation of shaft 43 relative to the sensing lever, thereby to adjust the position of shift link 131 angularly of the sensing lever about the axis of shaft 43.

Shaft 43 extends exteriorly of the gear box away from chassis plate 134 to mount three cams 148, 149 and 150. Three microswitches S9, S11 and S12 are mounted to the adjacent face of the gear box for cooperation with cams 148, 149 and 150, respectively, via cam follower rollers 151 supported on the free ends of cantilever springs 152 which, when deflected, operate the normally open switches. Switch S9 is the lockout switch associated with reel station No. 1 as shown in FIG. 3I. Switch S11 is the forward mode limit switch for motor 133 and switch S12 is the reverse mode limit switch for the motor. Cam 148 is contoured so that switch S9 is closed when shift link 131 is in either of the positions illustrated in the solid and dashed lines in FIG. 4, but is open when the shift link is intermediate these two limiting positions. Cam 149 is contoured so that switch S11 is open only when shift effective upon drive belt 123 is reversed from that relation- 

